Experimental and kinetic modeling study of the low- and intermediate-temperature oxidation of dimethyl ether

Recent experiments on low-temperature oxidation of dimethyl ether (DME) at atmospheric pressure reveal much lower fuel conversion than the predictions of all published models. Consistent with previous measurements, the present work on DME oxidation in a laminar flow reactor between 400 and 1160K at atmospheric pressure also confirmed this behavior. To reduce the gap between model predictions and experimental results, both regarding key oxygenated species and fuel conversion, an extended and updated kinetic model of DME oxidation was developed from the widely used model of Z. Zhao, M. Chaos, A. Kazakov, F.L. Dryer, Int. J. Chem. Kinet. 40 (2008) 1-18. The development of the model focused on the reaction sequences that affect the low-temperature oxidation reactivity. In particular, the reactivity of DME oxidation in the low-temperature regime and at atmospheric pressure can now be predicted. This is possible upon the inclusion of an additional, chemically-activated pathway of CH₃OCH₂ reaction with O₂, as well as of the new decomposition chemistry of OCH₂OCHO radical, investigated theoretically in this work. The present model was examined against species concentrations in DME oxidation from low to intermediate temperatures and shock tube ignition delay times. It shows satisfactory performance in reproducing the respective literature data.